1. Field
The present invention relates to a method and a device for bonding sheets of material. It should be appreciated that, the term “sheets” should is restricted to plastic sheets, the term “sheets” also includes all other suitable materials for producing a surface skin, such as, for example, leather, synthetic leather, non-wovens, textiles, etc.
2. Discussion of Related Art
Components, such as, for example, interior trim panels for motor vehicles are designed with more than one surface to achieve specific aesthetic effects. For example, two-colored components can be produced by using different colored sheets. It is also conceivable to use different sheets to provide better protection for certain areas of a component that are exposed to a greater degree of wear.
In this regard, it is known, for example, to bring the sheets to be bonded into flat contact and to weld them to each other. However, one drawback with this technology is that a weld mark results in the visible region of the components. To satisfy aesthetic demands it is therefore generally necessary to cover the weld mark with decorative coverings or fittings.
DE 298 23 765 U 1 describes bonding sheets for an interior trim panel for vehicles to each other in a groove perpendicular to the sheet surface. To achieve a reliable bond in this regard, a deep groove is created perpendicular to the sheet surface. The sheets are then back-foamed. In this regard, the deep groove acts as a barrier to the foam flow, making back-foaming without the formation of voids difficult.
U.S. Pat. No. 5,304,273 describes bonding the sheets via a groove, whereby the sheets are also held together by a clip. In this regard, the sheets can be shaped to provide a sheet with a U-shaped end area into which a leg on the end area of the second sheet engages. The drawback of employing the clip, however, is the additional assembly stage required.
JP 04143136 A describes bonding sheets to each other via a groove and gluing the sheets to each other in an overlapping region next to the groove. To accomplish this, the groove is formed in a first sheet and the second sheet is introduced into the groove in an unshaped fashion and glued to the first sheet on the overlapping region. Then the groove with the end area of the second sheet inserted therein is shaped so that the second sheet is provided with a hook. Then the sheets are turned and placed in a mold. The bond between the first sheet and the second sheet is reinforced in the mold by a glass fiber layer. One drawback of the method is the necessity of turning the sheets before reinforcing the bond by the glass fiber layer.